estimate these?

Question

4 1/3*2 4/5 [8 or 15 or 9 or 12?
5 9/10*2 2/3 [10 or 15 or 18 or 12?

Answer 1

here's a couple ways to "estimate:"

4 1/3 = 13/3
2 4/5 = 14/5

13/3 * 14/5 = 13 * 14 / 15 which is pretty close to 12 (the three numbers are close together and the number dividing is the largest)

5 9/10 = 59/10
2 2/3 = 8/3

59/10 * 8/3 = 59 * 8 / 30 which is close to 60 * 8 / 30 = 2 * 8 = 16

Answer 2

86765 1/7

Answer 3

4.3 * 2.8 = 12ish

5.9 * 2.667 = 15.7ish