Question

Study the pattern and answer the following:

$18\times 1=18$

$18\times 2=36$ (add $2$ tens and $2$ones less than $18$i.e. $\left[20+16\right]$)

$18\times 3=54$ (add $2$ tens and $2$ones less than $36$i.e. $\left[20+34\right]$)

$18\times 4=72$ (add $2$ tens and $2$ones less than $54$i.e. $\left[20+52\right]$)

Now, continue this pattern

$$\begin{gathered} 18\times 5=......... \\ 18\times 6=......... \\ 18\times 7=......... \\ 18\times 8=......... \\ 18\times 9=......... \\ 18\times 10=......... \end{gathered}$$

Answer 1

Finding the missing numbers:

By observing the pattern, we get

$18\times 1=18$

$18\times 2=36$ (add $2$ tens and $2$ ones less than $18$i.e. $\left[20+16\right]$)

$18\times 3=54$ (add $2$ tens and $2$ ones less than $36$i.e. $\left[20+34\right]$)

$18\times 4=72$ (add $2$ tens and $2$ ones less than $54$i.e. $\left[20+52\right]$)

$18\times 5=90$ (add $2$ tens and $2$ ones less than $72$i.e. $\left[20+70\right]$)

$18\times 6=108$ (add $2$ tens and $2$ ones less than $90$i.e. $\left[20+88\right]$)

$18\times 7=126$ (add $2$ tens and $2$ ones less than $108$i.e. $\left[20+106\right]$)

$18\times 8=144$ (add $2$ tens and $2$ ones less than $126$i.e. $\left[20+124\right]$)

$18\times 9=162$ (add $2$ tens and $2$ ones less than $144$i.e. $\left[20+142\right]$)

$18\times 10=180$ (add $2$ tens and $2$ ones less than $162$i.e. $\left[20+160\right]$)

Hence, $18\times 5=90$, $18\times 6=108$, $18\times 7=126$, $18\times 8=144$, $18\times 9=162$, $18\times 10=180$