# A number theory problem by Vraj Mistry

**Number Theory**Level pending

Rihanna brought home 150 pens but while packing them, she misplaced some of them. When her brother asked how many she had misplaced, she told him:

If you count in pairs, one will remain

If you count in a group of three, two will remain

If you count in a group of four, three will remain

If you count in a group of five, four will remain

If you count in a group of six, five will remain

If you count in a group of seven, nothing will remain.

How many pens do you think has she misplaced ?

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**That seems reasonable.**Find out if you're right!

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