Basic Calculation:26

                          One Line Multiplication

          Multiplication of a four digit no. by a three digit no.

              2436                5243                  6354                  3469 

             × 324               × 451                × 263                 × 532  

   7₁8₂9₄2₂6₂4     23₃6₃4₃5₁93     16₄7₅1₅1₄0₁2     18₃4₅5₇5₄0₁8     

Detailed Explanation: This is the general rule of multiplication of any four digit number by another three digit number.

For example, when we multiply 2436 by 324; we first multiply 6 by 4, we get 24, so 4 is written and 2 is carry over.

Next we multiply 3 by 4, which is 12 and then 6 by 2, which is 12. We add 12, 12 and 2 (carry over), we get 26. 6 is written and 2 is carry over.

Then we multiply 4 by 4, which is 16; 6 by 3, which is 18 and then 3 by 2, which is 6. We add 16, 18, 6 and 2 (carry over), we get 42. 2 is written and 4 is carry over.

Then we multiply 2 by 4, which is 8; 3 by 3, which is 9 and then 4 by 2, which is 8. We add 8, 9, 8 and 4 (carry over), we get 29. 9 is written and 2 is carry over.

Again, we multiply 2 by 2, which is 4 and then 4 by 3, which is 12. We add 4, 12 and 2 (carry over), we get 18. 8 is written and 1 is carry over.

Lastly, we multiply 2 by 3, which is 6 and we add 6 and 1, which is 7. So,   7₁8₂9₄2₂6₂4  is the answer.