Given that $$\overline{ab} \times 7= \overline{a0b}$$, Find $$\overline{ab}$$.     Below is Janice\textquotesingle s attempt at solving the question.  $7 ab$ = $10a$ + $b$  $7 a \times b$ = $10a$ + $b$  $7 a \times b$ = $7a$ + $3a$ + $b$  $3a + b$ = $b$  $a$ = $0$  $b$ = $0$  $$\overline{ab}$$ = $0$.     Janice: "$\cdots$ ".  She thought that the answer was a bit strange but could not figure out what went wrong! Can you help Janice out? Identify her error and find $$\overline{ab}$$. 
Overseas Competition->Knowledge Point->Number Theory Modules->Place Value and Number Bases->Applying the Principle of Place Value