Mental Math
272 + 313 = ?
585
Find the missing number.
8 + 9 = ? + 8
9
78 + 34 = ?
112
Round to the nearest ten to estimate the sum of
472 + 287 =
760
4,461 + 2,124 =
6,585
493 + 207 = ?
700
87 + 0 = ?
87
294 + 133 = ?
427
Round to the nearest hundred to estimate the sum of 1,245 + 482 =
1,700
112,450 + 53,476 =
165,926
545 - 335 + ?
210
Find the missing number.
48 + 83 = 83 + ?
48
123 + ? = 175
52
Round to the nearest ten to estimate the difference of
3,242 – 2,567 =
660
7,769 – 3,435 =
4,334
838 - 724 = ?
114
Find the missing number.
(5+ 2) + 3 = (3+ ?) +5
2
282 + ? = 496
214
Round to the nearest ten thousands place to estimate the sum of
28,392 + 72,284 =
100,000
98,600 – 54,587 =
44,013
211
Find the missing number.
(381 + 121) + 282 = (? + 121) + 381
282
(26 + 32) + ? = 127
69
Round to the nearest thousands place to estimate the difference of
34,279 - 18,829 =
15,000
Cady has 435 glass marbles. She has 221 plastic marbles. She gave 150 plastic marbles to her brother. How many total marbles does Cady have?
506