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Add multiple numbers together with step-by-step solutions. Supports decimals, negative numbers, and shows the complete working.
Addition is one of the four basic arithmetic operations. It combines two or more numbers to find their total, or sum. The numbers being added are called addends, and the result is called the sum.
The order of addends doesn't change the sum.
Grouping doesn't change the sum.
Adding zero doesn't change the number.
Adding a number's opposite gives zero.
Look for pairs that add to 10: 8 + 7 = 8 + 2 + 5 = 10 + 5 = 15
For 47 + 38: Add 40 + 30 = 70, then 7 + 8 = 15, finally 70 + 15 = 85
For 98 + 47: Think 100 + 47 - 2 = 147 - 2 = 145
Line up the numbers by place value (ones under ones, tens under tens), then add column by column from right to left, carrying over when the sum exceeds 9.
Adding a negative number is the same as subtracting its absolute value. For example, 5 + (-3) = 5 - 3 = 2. When adding two negative numbers, add their absolute values and make the result negative: (-3) + (-4) = -7.
Line up the decimal points, then add as with whole numbers. Fill in zeros as placeholders if needed. For example: 3.5 + 2.75 → 3.50 + 2.75 = 6.25
Use the formula n(n+1)/2. For 1 to 100: 100 × 101 / 2 = 5,050. This formula was famously discovered by young Gauss.
Addition is commutative because the total quantity doesn't depend on the order you combine items. Whether you have 3 apples and add 5 more, or have 5 apples and add 3 more, you end up with 8 apples.
You can verify addition by: 1) Adding in reverse order, 2) Subtracting one addend from the sum (should give the other addend), or 3) Using estimation to check if the answer is reasonable.