Question

Which of the following is closest to 19.9 times 199?

A. 4000 B. 3990 C. 3980 D. 3970 E. 3960

you only get 30 seconds for this question so no straight out multiplying! (NO CALCULATORS EITHER) i think the distributive property is used but I don't know how so please help meeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

Answer 1

E 3960

Explanation:

Round 19.9 and 199 to 20 and 200

20*200 = 4000

Now subtract 20

20 * (200-1) = 4000-20

20 * 199 = 4000-20

20*199 = 3980

.1 of 200 is 20

so subtract 20

(20-.1) *200=3980-20

19.9 *200 =3960

(20-.1) *(200-1) = 3960