Rounding
Round 42 to the nearest ten
40
When adding, which place value must you start in?
The ones place
True or False? When subtracting, you start with the ones place, then go to the hundreds, and then the tens?
False. It's ones -> tens -> hundreds.
Estimate the sum of 723+141 by rounding to the nearest 100.
700+100=800
Round 94 to the nearest hundred
100
Add 291+627=
918
How do you know you need to regroup when subtracting?
When you can't subtract numbers in a place value because the number on the bottom is larger than the number on the top.
Estimate the sum of 542+159 by rounding each addend to the nearest ten.
540+160=700
Round 125 to the nearest ten
130
How do you know you need to regroup when adding?
When you get a sum in the ones or tens place that is 10 or more
Do you have to regroup when subtracting 492-321
No
Estimate the sum of 482+325 by rounding to the nearest 100.
500+300=800
Round 949 to the nearest hundred
900
Do you have to regroup when adding 572+419
Yes, you have to regroup the ones.
Subtract 943-261
682
Estimate the difference of 345-297 by rounding to the nearest 10.
350-300=50
Recite the rhyme for rounding
5 or more, let is soar
4 or less, let it rest
Add 192+284+357
833
Subtract 626-357
269
Estimate the difference of 723-569 by rounding to the nearest 10
720-570=150