What is equal to 6000 plus 90?
We can find the missing number by adding together 6000 and 90. There are no ones to add. So we have a total of zero in the ones column. We need to add nine tens to the zero in the tens column, which gives us nine tens. There’s nothing to add to the zero in the hundredths column and nothing to add to the six in the thousands column.
6000 plus 90 is 6090. All we had to do was add nine tens to 6000. 6090 is equal to 6000 plus 90.