What is the sum of the multiples of 11 from 11 to 891?

Answer 1

11 + 22 + 33 + ... + 869 + 880 + 891 = 36531

(Any Number Multiplied by 11- "BOOKENDS")

example: 463819 * 11= ??

Always start with putting down the first number, in this case, "4". Then starting with the first number, 4, add the first to the second, 4+6=10, put the 0 down and carry the 1 above the number 4, then add the second plus the third, 6+3=9, then the third number plus the forth, the fourth number plus the fifth number and so on until the last Two (2) are added. Finish up by putting the last number (9), on the end. In your process If you have a digit larger than 9, carry the the number in the 10's place back to the left. Your bookends are the 4 and 9. Your Eleven multiples will always have the last number on the end and the first number will be the same until you carry any Ones (1's) back.

463819 * 11

start with the 4

4 and (4+6=10) is now 40 carry the One (1) to the left makes it 50

50 and (6+3=9) is 509

509 and (3+8=11) is now 5091, carry the 1 back makes it 5101.

5101 and (8+1=9) is now 51019

51019 and (1+9=10) is now 51090 carry the 1 back makes it 510200

And finally take the last number in 463819 and put it on the end gives you 5,102,009

If you had 110, 1,100, 11,000... you would follow the above as described and add the number of Zero's to the end such as 110 has One (1) zero, 1,100 has Two (2) and So on... 463819 * 110 would be 51,020,09(0), 1100 would be 510,200,9(00), and so on.