Say you were solving 27 + 19. If you were planning on using the friendly numbers strategy, you'd look at the first addend, 27, and determine that the closest "friendly number" here is thirty, which you'd get by adding 3. From there, you can jump to the next friendly number, forty, by adding another 10. So far you'd've added 13, and you'd need another 6 for that too add up to 19, your second addend. After adding 3, 10, and 6 to 27, you'd find your sum, or "final answer"- 46.
I hope this was what you were looking for!
