Some number minus 104 equals 381. Can you find out what the missing number is?
Let’s imagine that inside this yellow rectangle is our missing value. We don’t know how much it is. We know that we took 104 away from this value. And after we took that 104 away, there was 381 left.
To find how much was in our box when we started, we need to add what we took away, the pink part, with what was remaining, the blue part. If we add 104 plus 381, we will know what we had to start with.
We can line the two values up vertically and then add. Starting in the units position, four plus one equals five. In the tens place, we have zero plus eight equals eight. In the hundreds place, one plus three equals four. The number we started with would have been 485. 485 minus 104 equals 381.