A ? B = C

Logic Level 2

Fill in each square on the left with a digit (0 to 9), and fill in each circle with any one of the 4 arithmetic operations $(+, -, \times, \div )$ .

We can get many numbers like:
$\begin{array} { c c c c c } 3 & - & 2 & = & 1 \\ 1 & \times & 2 & = & 2 \\ 2 & + & 1 & = & 3 \\ 1 & + & 3 & = & 4 \\ & & \vdots & & \\ \end{array}$

What is the smallest positive integer that we cannot achieve?

19 23 25 17

1 solution

Syed Hissaan
Feb 24, 2017

since we we can get $17$ as $9+8=17$ , the next smallest number is $19$ since it is a prime we can not get it by $(\times,\div,-)$ .moreover we can not get it by addition because the greatest number in the set is $9$ in order to get $19$ we must have at least $10$ . so 19 is the answer .

A ? B = C

1 solution

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