78x10 = 780 To multiply any number by ten just add a zero to the number. 230X10 ==2300 123X10 = 1230 very easy.
10/13 = ?/78 78/?= 13 so ? = 6 10/13 x 6/6 = 60/78 You can also cross multiply 78x10/13=60, but if you have to use multiplying by one, use the above method.