Exponents Followup 1

WALT:Solve fraction facts using my knowledge of my timetables
One thing that I learnt from this strategy was that:
1/3 of 21=7 because
3 x 7=21
7+7=14
14+7=21

Also my other strategy was:
7x2=14
7+7=14                   2+2+2+2+2+2+2=14