(1)298+ 184, the closest' answer is ().

①500 ②470 ③480

(2)723- 144, and the closest answer is ()

①580 ②570 ③600

(3)5 13+322, and the result of accurate calculation is ()

①830 ②800 ③835

Second, estimate first, and then calculate accurately:

837- 168 7 13- 144

Estimate: estimate:

Good: good:

Third, say which integer the following number is close to (it can be in various forms)

837 725 156 8 1 1 189 682 129 34 1

How do you estimate it?

Fourth, first use integers to estimate, and then accurately calculate.

5 12+ 189 725- 156

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