Answer:
The answer to your question is below
Step-by-step explanation:
4.-
4a. 72
_x 9
638
4b. The error this student is doing is that he multiplies the first number but he must add the decenes of this result to the result of the multiplication of the second number and he is not doing that.
4c.- I told him the correct way to solve multiplications.
a) Multiply the first number and only write the units.
b) If the are decenes add then to the units of the result of the multiplication of the second number.
Example
72 9 x 2 = 18
x9 Just write the 8
8
72
x 9
648 9 x 7 = 63 + 1 from the previous operation
= 64
