Rounding/Estimating
Round the addends to the nearest ten. Estimate the sum.
66
+ 11
_____
+ 10
____
80
Regroup ones as tens.
5 tens 13 ones
___tens and ___ ones
6 tens and 3 ones
Add mentally. Add 10 to:
12, 22, 32, 42
__, __, __, __
22, 32, 42, 52
Todd collects 27 shells at the beach. Nora and Joe collect 26 shells each. How many shells do Todd, Nora, and Joe collect in all?
They collect 79 shells in all.
57 + 29 = ?
86
Round the addends to the nearest ten. Estimate the sum.
44
+ 32
_____
40
+ 30
_____
70
Regroup ones as tens.
4 tens 15 ones
___tens and ___ ones
5 tens and 5 ones
Add mentally. Add 2 to:
14, 24, 34, 44
__, __, __, __
16, 24, 36, 46
There were 48 children on a boat ride. A dozen more children join them. How many children are there on the boat ride then?
There are 60 children on the boat ride.
77 + 13 = ?
90
Round the addends to the nearest ten. Estimate the sum.
26
+ 55
_____
30
+60
_____
90
Regroup ones as tens.
10 tens 11 ones
___tens and ___ ones
11 tens and 1 one
Add mentally. Add 6 to:
42, 52, 62, 72
__, __, __, __
48, 58, 68, 78
In the school play, Clara sees 35 singers and 36 dancers. About how many children does Clara see on stage in all?
Clara sees about 71 children in all.
51 + 8 = ?
59
Round the addends to the nearest ten. Estimate the sum.
34
+ 61
_____
+60
____
90
Regroup ones as tens.
2 tens 10 ones
___tens and ___ ones
3 tens and 0 ones
Add mentally. Add 11 to:
30, 40, 50, 60
__, __, __, __
31, 41, 51, 61
Al reads 17 stories about far away places to visit. Sandy reads 12 more stories than Al. How many stories do they read in all?
They read 46 stories in all.
35 + 52 + 12 = ?
99
Round the addends to the nearest ten. Estimate the sum.
99
+ 25
_____
100
+ 30
____
130
Regroup ones as tens.
5 tens 19 ones
___tens and ___ ones
6 tens and 9 ones
Add mentally. Add 30 to:
30, 40, 50, 60
__, __, __, __
60, 70, 80, 90
There were two dozen kids on the playground. Thirteen more kids came to play after school. How many kids were on the playground in all?
There were 37 kids on the playground in all.
65 + 4 + 28 = ?
97