[Chapter 5.4] Rounding and Estimation: Snap to the Nearest, Check the Size | Pre-Algebra

A length of 14.7382 meters is about fifteen meters. This calm, step-by-step explainer shows what rounding really does, and how an estimate catches a wrong answer. You'll see: • rounding as snapping to the nearest multiple • why one digit is enough to decide • carrying a nine that rounds up • why the exactly-five tie is a convention • working backward to the inputs • estimating before you compute • catching a misplaced decimal point • seven worked examples The full lesson, with worked examples and practice: https://mathbyfirstprinciples.org/pre... 0:00 Welcome, and what you'll learn 1:27 Rounding means snapping to the nearest 2:09 You only look at one digit 2:43 Why one digit is enough 3:43 Rounding on the grid, and repeating decimals 4:32 Worked Example 1: the nearest whole number 5:11 Worked Example 2: the nearest hundredth 5:53 Worked Example 3: when a nine rounds up 6:52 The exactly-five case is a convention 7:40 Worked Example 4: two ties 8:15 Working backward 8:46 Worked Example 5: which numbers round to seventy 9:40 Estimation: round first, then compute 10:47 Worked Example 6: estimating a sum 11:41 Estimation as a reasonableness check 12:16 Worked Example 7: a bill that rings up wrong 13:00 Key takeaways Narration is voiced with text-to-speech. Also available in Spanish, Hinglish, and Mandarin. #math #prealgebra