A number when divided by 14 or 13 leaves a remainder 3. Find the least possible value of that number?

three is the only such number

explanation:
the no's that leave a remainder of 3 when divided by 14 are 3 17 31 45 73 ...
or they are generated by the formula
y = 14x + 3

the no's that leave a remainder of 3 when divided by 13 are 3 16 29 42 ...
or they are generated by y = 13x + 3

these equations, when graphed, are two straight line that intersect only at (0,3)

3 ÷ 14 = 0 with remainder 3
3 ÷ 13 = 0 with remainder 3