How many multiples of 4 are there between 16 and 260 ?

BTGmoderatorDC wrote: ↑

Sat Nov 12, 2022 12:32 am

How many multiples of 4 are there between 16 and 260 ?

A. 128
B. 64
C. 62
D. 61
E. 60


OA E

Source: Princeton Review

If you're not good at remembering formulas, then another option is to look for a pattern.
So, we want to know how many terms are in the sequence 20, 24, 28, . . .. 252, 256

Notice that:
20 = 4(5)
24 = 4(6)
28 = 4(7)
32 = 4(8)
.
.
.
252 = 4(63)
256 = 4(64)

So, the number of terms in the sequence 20, 24, 28, . . .. 252, 256 is equal to the number of integers from 5 to 64 inclusive.

Well we have a formula (an easy formula) for finding this. We know that the number of integers from x to y inclusive is equal to y-x+1

So, the number of integers from 5 to 64 inclusive is equal to 64-5+1 = 60

Answer: E

BTGmoderatorDC wrote: ↑

Sat Nov 12, 2022 12:32 am

How many multiples of 4 are there between 16 and 260 ?

A. 128
B. 64
C. 62
D. 61
E. 60


OA E

Source: Princeton Review

The number of multiples of 4 between 16 and 260 is:

(256 - 20)/4 + 1 = 236/4 + 1 = 60

Answer: E