Respuesta :

64 x 10 = 640

Easier way to simplify :

64 x 1 = 64 and then put the 0 at the end which = 640
640

If you are multiplying by a 10ths value, you always add the number of zeroes behind the value of 10 to the number

64*10- there is one zero after 1, so you would add a zero behind 64