The sum of $1 + 9 + 7 + 8$ is:

$1 + 9 + 7 + 8 = 25$

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Here are 5 related questions to expand on this information:

1. What is the sum of $5 + 3 + 2 + 6$?
2. How do you add numbers in a sequence efficiently?
3. What is the difference between adding positive and negative numbers?
4. How does carrying work in addition when sums exceed 10?
5. Can you explain how to add decimals or fractions?

Tip: When adding a sequence of numbers, grouping them into pairs or sets that sum to 10 can make mental math easier.