(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.
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
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