+1090 $${\mathtt{78}}{\mathtt{\,\times\,}}{\mathtt{500}} = {\mathtt{39\,000}}$$
A way you can do problems like this in your head is doubling one number and halving the other.
Ex:
$${\mathtt{500}}{\mathtt{\,\times\,}}{\mathtt{2}} = {\mathtt{1\,000}}$$
78 ÷ 2 = 39
Then you add the three zeros to 39 (the tens trick.) and you have the answer quickly and easily!
+1090 $${\mathtt{78}}{\mathtt{\,\times\,}}{\mathtt{500}} = {\mathtt{39\,000}}$$
A way you can do problems like this in your head is doubling one number and halving the other.
Ex:
$${\mathtt{500}}{\mathtt{\,\times\,}}{\mathtt{2}} = {\mathtt{1\,000}}$$
78 ÷ 2 = 39
Then you add the three zeros to 39 (the tens trick.) and you have the answer quickly and easily!
