Subtracting
39 - 22 =
17
26 + 38 =
64
Using front-end estimation to the nearest ten: 65 - 27
70 - 30 = 40
60 - 20 = 40
60 - 30 = 30
Using front-end estimation to the nearest 10: 46 + 72 =
50 + 70 = 120
40 + 70 = 110
50 + 80 = 130
50 - 26 =
24
97 + 25 =
122
Using front-end estimation to the nearest ten: 88 - 59 =
90 - 60 = 30
80 - 60 = 20
80 - 50 = 30
Using front-end estimation to the nearest hundred: 24 + 49 =
20 + 50 = 70
20 + 40 = 60
30 + 50 = 80
81 - 48 =
33
148 + 41 =
189
Round 864 to the nearest hundred.
900
Using front-end estimation to the nearest hundred: 229 - 163
200 - 200 = 0
220 - 160 = 60
230 - 160 = 70
200 - 150 = 50...
Using front-end estimation to the nearest hundred: 120 + 287=
100 + 300 = 400
120 + 280 = 400
120 + 290 = 410
100 + 200 = 300...
71 - 26 =
45
138 + 129 =
267
Round 743 to the nearest 100.
700
Using front-end estimation to the nearest hundred: 523 - 289
500 - 300 = 200
520 - 290 = 230
520 - 280 = 240
500 - 200 = 300
Using front-end estimation to the nearest hundred: 423 + 513 + 892 =
400 + 500 + 900 = 1800
(there other other combinations that are also good, but the answer should be pretty close to this)
140 - 131 =
9
202 + 345
547
Steven has 555 marbles in his collection. When asked how many he has to the nearest hundred, he should say:__________
600
Using front-end estimation to the nearest hundred: 875 - 129
800 - 100 = 700
870 - 120 = 750
900 - 100 = 800
900 - 200 = 700...
Using front-end estimation to the nearest hundred: 174 + 425 + 212
200 + 400 + 200 = 800
(there are also other possibilities but the answer needs to be pretty close to this)