#1**+1 **

(100, 120, 140, 160, 180, 200, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 460, 480, 500, 520, 540, 560, 580, 600, 620, 640, 680, 700, 720, 740, 760, 780, 800, 820, 840, 860, 900, 920, 940, 960, 980)=41 Numbers.

220, 440, 660, 880 are multiples of both 20 and 55, which are excluded from the above count.

Guest May 26, 2019

edited by
Guest
May 26, 2019

#2**+1 **

Thanks Guest.

How many positive 3-digit numbers are multiples of 20, but not of 55?

100 to 999

45 are multiples of 20

To be a multiple of 20 and of 55 then the factors must be 2*2*5*11*X = 220X

1000/220=4.5..

So X can be 1,2,3, or 4

Hence there are four 3 digit numbers that are multiples of both 55 and 20

So the answer is 45-4 = 41

Guest like guest already told you

Melody May 27, 2019