How many three digits are positive integers there whose digits are 2 or 5?

8.

A way to work this out is figure out how many possible digits can go in each place value position (units, tens, hundreds) and multiply these together. Since there are 2 possible digits that can go in each position and there are three positions, you would go: 2 x 2 x 2 = 8

Want a list?

222

225

252

255

555

552

525

522