<Tr> <Td> 4 = 16 </Td> <Td> 9 = 81 </Td> <Td> 14 = 196 </Td> <Td> 19 = 361 </Td> <Td> 24 = 576 </Td> <Td> 29 = 841 </Td> </Tr> <Tr> <Td> 5 = 25 </Td> <Td> 10 = 100 </Td> <Td> 15 = 225 </Td> <Td> 20 = 400 </Td> <Td> 25 = 625 </Td> <Td> 30 = 900 </Td> </Tr> <P> It may be useful to be aware that the difference between two successive square numbers is the sum of their respective square roots . Hence if you know that 12 × 12 = 144 and wish to know 13 × 13, calculate 144 + 12 + 13 = 169 . </P> <P> This is because (x + 1) − x = x + 2x + 1 − x = x + (x + 1) </P>

If 7 times a number is 84 what is 4 times the number