Compare 40/90 and 42/21, Which fraction is greater?

Compare 40/90 and 42/21

1^st number: 40/90, 2^nd number: 2 0/21

40/90 is smaller than 42/21

Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630

Next, find the equivalent fraction of both fractional numbers with denominator 630
For the 1st fraction, since 90 × 7 = 630,
40/90 = 40 × 7/90 × 7 = 280/630
Likewise, for the 2nd fraction, since 21 × 30 = 630,
42/21 = 42 × 30/21 × 30 = 1260/630
Since the denominators are now the same, the fraction with the bigger numerator is the greater fraction
280/630 < 1260/630 or 40/90 < 42/21

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