At a party, every seventh guest gets a keychain and every tenth guest gets a cup. What is the position of the first guest that will get both a keychain and a cup?
Multiples of 7: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70
Multiples of 10: 10, 20, 30, 40, 50, 60, 70
Position of first guest that gets both a keychain and cup
= Lowest common multiple of 7 and 10
= 70
Answer(s): 70