Multiples of 50 are easy to spot because they all end in 50 or 00.

Look at the first few multiples of 50 and check that this is true.

50, 100, 150, 200, 250, 300, 350, 400, 450 ...

Examples

200, 350, 450, 900, 1250, 2000 are multiples of 50.

They all end in 50 or 00.

60, 240, 1430, 1660 are NOT multiples of 50.

None of them ends in 50 or 00.