840
They are all multiples.
These are some of the multiples of 84....84,168,252,336,420,504,588,672,756,840,924...
Those are known as "common multiples". The smallest POSITIVE of these common multiples is called the "least common multiple".
The GCF is 120.
All multiples of 840 are common multiples of 60 and 280
840
840
210, 420, 630, 840 . . .
840, 1680, 2520
420, 840, 1260 and so on.
280, 560, 840
210, 420, 630, 840, 1050 Five common multiples. Only one can be least.
42000
168, 336, 504, 672, 840
140, 280, 420, 560, 700, 840, 980 +140 . . .
3 Least Common Multiples of 12 and 35 are 420, 420 and 420.There is ONLY one Least Common Multiple.The three common multiples of 12 and 35 which are the smallest are the first three multiples of their Least Common Multiple, namely 420, 840 and 1260