Mathematics Grade 4 Rounding Whole Numbers

hello my favorite grade four mathematicians how have you been hope that you have been staying safe and healthy am your mathematics teacher and in today's lesson we will be focusing on rounding numbers so boys and girls grab your pens grab your notebooks and let's take an adventure in mathematics land before we delve into our lesson want to share quote with you it was shakuntala devi who said without mathematics there is nothing you can do everything around you is mathematics everything around you is numbers so boys and girls fast near seat belts let's take this adventure in mathematics land our topic for today as told you previously is rounding whole numbers when we round numbers we change them to simpler one with the same value it is like an estimate let's look at some rounding words estimate close enough roughly approximate now that we know what rounding is let's delve in now into the meat of the matter let's choose random number 36 when wrong in numbers it is important to know the place value it helps us to know exactly how to wrong the number i'm sure you remember what place value is in case you don't remember the place value of digit is its position in the number in the number 36 what is the place value of the six once what is the place value of the three tens when wronged in numbers you always will have two options round up or round down examine now how to round whole numbers to the nearest ten when round the numbers to the nearest ten we must look at the digit in the spot before the number we are rounding to or as like to see the number hitting at the back door if that number is 5 or more you add 1 to the number in the tens position and change the number in the ones position to zero if the number is four or less we leave the number in the tens place as it is and change the one in the ones place to zero let's look at this example what would 36 rounded to the nearest tens be do what number are we rounding tens we said that when rounding numbers we look at the number we are rounding to first and then we look at the number that is in the place before that number in this case six is in the place before that number is six more than five or less than five six is more than five since six is more than five we add one to the number in the tens column and change the number in the ones column to zero so three plus one will give us four and the six is changed as zero so 36 rounded to the nearest tens is 40. let's look at another example what is 454 rounded to the nearest 10 what number are we rounding to we are rounding the number to the nearest ten what is the number in the tens place in that number the number in the tens place in that number is five so now that we would have identified our number that we are rounding let's identify the number in the position before that number or the number hitting on the back door that number is four is four more than five or is it less than five four is less than five we said if the number in the ones place is less than five we write back the number in the tens place as is and change the number in the ones place to zero so we will write back our four we will write back our five and we will change the four to zero so 454 rounded to the nearest 10 is 450 boys and girls it is now time for our tips and tricks segment now this is tip and trick for when you are rounding numbers to nearest ten listen carefully now you think about the two tens number is found between you can place them on number line counting intense the number closer to it would be the nearest 10. let's quickly look at this example what is 46 rounded to the nearest 10 so let's get our number line up there counting in tens so we know that number line always starts with zero so we have our 0 10 20 30 40 50 60. let's stop at 60. where do you think 46 is found on this number line which two numbers 46 falls between did you say 40 and 50 yes you are absolutely correct 46 falls between 40 and 50. now which number is it closer to is 46 closer to 40 or is 46 closer to 50 did you say 50 well then you are absolutely correct 46 is closest to 50. so 46 rounded to the nearest 10 is 50. boys and girls let's move on to rounding whole numbers to the nearest hundred when rounding numbers to the nearest hundred we must look at the digit in the spot before the number we are rounding to or as would see the number hitting on the back door in other words boys and girls when rounding numbers to the nearest hundreds we look at the number in the tens place if the number is five or more you add one to the number in the hundreds place and you change the number in the tens and the ones place to zeros if the number is less we leave the number in the hundreds place as is and we change the numbers in the tenths and the ones place to zero so when round the numbers to the nearest hundred you look at the number in the tens position let's quickly look at an example round 472 to the nearest hundred do what number are we rounding to the nearest hundred therefore we have to look at the digit in the tens position what is the number in the tens position seven is seven more than five or is it less than five boys and girls seven is more than five we said if the number in the tens place is seven or more we add one to the number in the hundreds place and we change the numbers in the tens and the ones place to zero what is the number in the hundreds place four when one is added to that four it becomes five the rule said we change the numbers in the ones and the tens place to zero therefore four hundred seventy two rounded to the nearest hundred is five hundred let's look at example two approximate the number 2639 to the nearest hundred boys and girls did you notice used different word instead of rounding approximate it means the same thing all you're simply asked to do is to run 2 639 to the nearest hundred so let's identify our digit that we are rounding to we are rounding to the nearest hundred the number in the hundredths place is six let's identify the digit to the right of that number or as would say the number that is hitting that number's backdoor that number is three the number in the tens position is three greater than five or is it less than five we know that three is less than five we establish when the number in the tens place is less than five we leave the number in the hundreds place as is and we change the numbers in the tens and the ones place to zero so we write back over two we write back our six and we add two zeros since we are rounding to the nearest hundred boys and girls it is time for you to put into practice what you would have learned so here is an activity round the numbers below to the nearest ten number one 246 number two 8673 let's see what you have you should be finished by now 246. we are rounding to the nearest ten so we look at the number in the ones place what number is in the ones place boys and girls six is six more than five or is it less than five six is more than five and we learned that once the number in the ones place is more than five we add one to the number in the tens place and we change the number in the ones place to zero because we are rounding to the nearest therefore 246 rounded to the nearest 10 is 250 let's look at the other one 8 673 rounded to the nearest ten let's identify the number we are rounding to the nearest ten the number in the tens place is seven which number is to the right of that number or which number is hitting the back door of that number three is three more than five or is it less than five three is less than five we learnt that if the number in the ones place is less than five we rewrite the number as is and change the number in the ones place to zero so we write back our eight our six our seven and we change the three to zero eight thousand six hundred seventy three rounded to the nearest 10 is boys and girls there is one other activity want you to do but this is in the form of problem timmy's father is an electrician he had roll of wire it measured 789 meters estimate to the nearest hundredth the amount of wire timmy's father had boys and girls did you notice used another rounding word estimate all it simply means is that you have to round 789 meters to the nearest hundred do you should be finished by now let's see what you have let's look at the number 789 let's identify the number we are rounding to we are rounding to the nearest hundreds seven is in the hundreds place what number is hitting on the back door of that number it is the number hitting on the back door of that number we learned that when rounded to the nearest hundreds we look at the number in the tens place it is in the tens place the rules say if it's five or more you add one to the number in the hundreds place and change the number in the tens and ones place to zero therefore 789 meters rounded to the nearest hundred is 800 meters boys and girls it is time for you to solve mystery in our mystery numbers segment today look at these clues and solve the mystery am six more than the number of days in december am 99 minus 62. what number am take 30 seconds to complete this boys and girls do you should be finished by now let's see if you got that mystery soul the first clue said am six more than the number of days in december how many days are there in december 31 the number is six more so we had to add 6 to 31 if we subtract 62 from 99 we will get total of 37 so the mystery number for the day is 37. excellent boys and girls thank you so much for solving that mystery now we have to bring the curtains down on our lesson today thank you boys and girls thank you for joining us boys and girls see you next time you