Albert added 346 + 51 and got a sum of 856. What did he do wrong?

Question

Albert made a mistake when adding 4 tens + 5 tens.

Albert did not align the digits according to their place value when he set up the problem.

Albert multiplied the two numbers instead of adding.

Albert forgot to carry a ten over to the next column of digits.

Answer 1

Albert's mistake can be attributed to improperly handling the addition of the digits in the correct place values, leading to an incorrect sum. The specific issue is:

Albert forgot to carry a ten over to the next column of digits.

Here's how the addition should look:

  346
+  51
-----
  397

When adding the "4" (from 346) and "5" (from 51) in the tens place, Albert should have correctly calculated that "4 + 5 = 9" and added that with 3 in the hundreds and 6 and 1 in the units place. Thus, the correct sum should be 397, not 856.