When things are grouped in twos, we can count them easily going up in 2s.

Count the candles.

2	4	6	8	10

There are 10 candles here.

When things are grouped in tens, we can count them easily going up in 10s.

Count the candles.

10	20	30	40	50

There are 50 candles here.

Shall we have a go at some counting?