What would be the result of 1+2+'3'

The output is going to be 33. Since 1 and 2 are numeric values, the result of the first two digits is going to be a numeric value 3. The next digit is a string type value because of that the addition of numeric value 3 and string type value 3 is just going to be a concatenation value 33. Other operationrs like 3 * '3' do yield correct results because the string is coerced into a number.