Estimate each of the following products by rounding off each number to nearest tens:
(a) 87 × 32
(b) 311 × 113
(c) 3239 × 28
(d) 1385 × 789
(a) Rounding off 87to nearest tens = 90
Rounding of 32 to nearest tens = 30
90 × 30 = 2700
(b) Rounding off 311 to nearest tens = 310
Rounding of 113 to nearest tens = 110
310 × 110 = 34100
(c) Rounding off 3239 to nearest tens = 3240
Rounding of 28 to nearest tens = 30
3240 × 30 = 97200
(d) Rounding off 1385 to nearest tens = 1390
Rounding of 789 to nearest tens = 790
1390 × 790 = 1098100