Make a 10
Make a 10 to subtract mentally.
94 - 59
59 --> 60 (+1)
94 - 60 = 34
34 (+1) =35
So, 94-59 = 35
Estimate. Round each number to the nearest ten.
86 - 64
86 --> 90
64 --> 60
90 - 60 = 30
Subtract to find the unknown.
86 - 17
69
Subtract across zeros to find the unknown.
100 - 55
45
Finish the rule:
When you subtract 0 from a number, you get ____?
Make a 10 to subtract mentally.
86 - 49
49 --> 50 (+1)
86 - 50 = 36
36 (+1) = 37
So, 86 - 49 = 37
Estimate. Round each number to the nearest ten.
550 - 244
550
244 --> 240
550 - 240 = 310
Subtract to find the unknown.
795 - 775
20
Subtract across zeros to find the unknown.
300 - 134
166
Finish the rule:
When you subtract a number from itself, you get ____.
zero
Make a 10 to subtract mentally.
67 - 29
29 --> 30 (+1)
67 - 30 = 37
37 (+1) = 38
So, 67 - 29 = 38
Estimate. Round each number to the nearest ten.
34 - 7
34 --> 30
7 --> 10
30 - 10 = 20
Subtract to find the unknown.
857 - 427
430
Subtract across zeros to find the unknown.
2,006 - 536
1,470
Mentally subtract 34 - 18 by breaking apart the smaller number.
18 = 14 + 4
34 - 14 = 20
20 - 4 = 16
34 - 18 = 16
Make a 100 to subtract mentally.
223 - 99
99 --> 100 (+1)
223 - 100 = 123
123 (+1) = 124
So, 223 - 99 = 124
Estimate. Round each number to the greatest place value.
388 - 311
388 --> 400
311 --> 300
400 - 300 = 100
Subtract to find the unknown.
$458 - $223
$235
Subtract across zeros to find the unknown.
1,007 - 972
35
The local zoo has 124 mammals and 97 reptiles. How many more mammals does the zoo have than reptiles?
124 - 97 = 27 mammals
Make a 100 to subtract mentally.
356 - 298
298 --> 300 (+2)
356 - 300 = 56
56 (+2) = 58
So, 356 - 298 = 58
Estimate. Round each number to the nearest hundred.
$3,257 - $189
$3,257 --> $3,300
$189 --> $200
$3,300 - $200 = $3,100
Subtract to find the unknown.
3,012 - 1,225
1,787
Subtract across zeros to find the unknown.
$9,006 - $7,474
$1,532
Determine rather an estimate or exact answer is required. Then solve.
In the third grade, there are 132 girls and 149 boys. How many more boys than girls are in the third grade?
Exact; 149 - 132 = 17 boys