Are you sure you want to leave?

Your test is still in progress. If you leave this page or go back now, all your attempt wil not be saved.

All the houses on a road are to be given new metallic numbers to attach to their front doors. The houses are numbered from 1 to 100. The metallic figure ‘6’ can be used the other way up as a ‘9’, so the same figure can be used either way.

How many of these figure ‘6’ or ‘9’ are needed for all the houses?