Instructors can:
- say the numbers and ask learners to fill in the
blanks.
Learners can:
- work in pairs and read the numbers to each other
and put the missing number in the blank.
1 2 3 
5 6 7 8
10 11 12 14 15 16 18
19 20 21 23 24 25 26
27 28 30 31 32 34 35
36 38 39 41 42 44
46 47 48