Multiplication is repeated addition. So, \(2 \times 10\) means to add \(10\) two times. \[2 \times 10 = 10 + 10 = 20\]

Here is \(10\) multiplied by the first few numbers; \begin{align} & 1 \times 10 = 10 \\ & 2 \times 10 = 10 + 10 = 20 \\ & 3 \times 10 = 10 + 10 + 10 = 30 \\ & 4 \times 10 = 10 + 10 + 10 + 10 = 40 \\ \end{align}

Adding tens is like counting in the tens place. So, to multiply a whole number by \(10\) you can add a \(0\) at the end. \[5 \times 10 = 50\] \[6 \times 10 = 60\]

This even works for large number. Let's multiply \(57\) by \(10.\) To multiply, add a \(0\) on the end of \(57.\) \[57 \times 10 = 570\]