123.
1230/10 = 123.
10
78x10 = 780 To multiply any number by ten just add a zero to the number. 230X10 ==2300 123X10 = 1230 very easy.
790
Two groups of five is ten
1240
Ten of them.
Ten.
there are 10 groups of 10
Your Mother
No/Yes they also used groups of hundred.
16
One thousand.