LCM for 21 and 55
What's the Least Common Multiple (LCM) of 21 and 55?
(One thousand, one hundred fifty-five)
Finding LCM for 21 and 55 using GCF's of these numbers
The first method to find LCM for numbers 21 and 55 is to find Greatest Common Factor (GCF) of these numbers. Here's the formula:
LCM = (Number1 × Number2) ÷ GCF
GCF of numbers 21 and 55 is 1, so
LCM = (21 × 55) ÷ 1
LCM = 1155 ÷ 1
LCM = 1155
Finding LCM for 21 and 55 by Listing Multiples
The second method to find LCM for numbers 21 and 55 is to list out the common multiples for both nubmers and pick the first which matching:
Multiples of 21: 21, 42, 63, 84, 105, 126, 147, 168, 189, 210, 231, 252, 273, 294, 315, 336, 357, 378, 399, 420, 441, 462, 483, 504, 525, 546, 567, 588, 609, 630, 651, 672, 693, 714, 735, 756, 777, 798, 819, 840, 861, 882, 903, 924, 945, 966, 987, 1008, 1029, 1050, 1071, 1092, 1113, 1134, 1155, 1176, 1197
Multiples of 55: 55, 110, 165, 220, 275, 330, 385, 440, 495, 550, 605, 660, 715, 770, 825, 880, 935, 990, 1045, 1100, 1155, 1210, 1265
So the LCM for 21 and 55 is 1155
Finding LCM for 21 and 55 by Prime Factorization
Another method to find LCM for numbers 21 and 55 is to list all Prime Factors for both numbers and multiply the highest exponent prime factors:
All Prime Factors of 21: 3, 7 (exponent form: 31, 71)
All Prime Factors of 55: 5, 11 (exponent form: 51, 111)
31 × 71 × 51 × 111 = 1155
Related Calculations
See Also
- Greatest Common Factor - Find the Greatest Common Factor (GCF) of two numbers
<a href="https://calculat.io/en/number/least-common-multiple-lcm-of/21--55">What is the LCM of 21 and 55? - Calculatio</a>
LCM Table
About "Least Common Multiple" Calculator
Least Common Multiple (LCM) also known as the Lowest Common Multiple or Smallest Common Multiple of 2 numbers - it is the smallest positive integer that is divisible by both numbers