Estimate the following products using general rule:

(a) 578 × 161

(b) 5281 × 3491

(c) 1291 × 592

(d) 9250 × 29

Make four more such examples.

(a) 578×161

Rounding off by general rule,

598 rounds off to 600

161 rounds off to 200,

So,

= 600×200 = 120000

(b) 5281×3491

Rounding off by the general rule,

5281 rounds off to 5000

3491 rounds off to 3000

So,

= 5000×3000

= 15000000

(c) 1291×592

Rounding off by general rule,

9250 rounds off to 1000

592 rounds off to 600

So,

= 1000×600

= 600000

(d) 9250×29

Rounding off by general rule,

9250 rounds off to 9000

29 rounds off to 30

So,

= 9000 × 30

= 270000