Estimate each of the following using general rules:

(a) 730 + 998

(b) 796 – 314

(c) 12,904 +2,888

(d) 28,292 – 21,496

Make ten more such examples of addition, subtraction and estimation of their outcome.

(a) 730+998

By rounding off to hundreds,

730 rounds off to 700 and,

998 rounds off to 1000,

So we have;

= 700+1000

= 1700

(b) 796-314

By rounding off to hundreds,

796 rounds off to 800 and,

314 rounds off to 300

We get,

= 800-300

= 500

(c) 12904+2822

By rounding off to thousands,

12904 rounds off to 13000 and,

2822 rounds off to 3000.

We get,

= 13000+3000

= 16000

(d) 28,296 – 21, 496

By rounding off to nearest thousands,

28,296 rounds off to 28000

21,496 rounds off to 21,000

We get,

= 28,000 – 21,000

= 7,000