Question

If Elon was born in 1999 and Ellie in 2001, the sum of their birth years would be .

• A. 4999
• B. 3999
• C. 4000
• D. 3000

Answer 1

The correct option is C 4000

Elon's birth year = 1999
Ellie's birth year = 2001

Sum of the birth years = 1999 + 2001

To find the sum, we add the birth years by writing the digits one below the other.


Ones place value
9 + 1 = 10
Put the 0 in ones place
Carry the 1 to tens place


Tens place value
1 + 9 + 0 = 10
Put the 0 in tens place
Carry the 1 to hundreds place


Hundreds place value
1 + 9 + 0 = 10
Put the 0 in hundreds place
Carry the 1 to thousands place


Thousands place value
1 + 1 + 2 = 4
Put the 4 in thousands place

Therefore, the sum of Elon's and Ellie's birth years is 4000.