47
Naming and writing three-digit numbers
Textbook: Part 2, lesson 45, pp. 10–11
GoalNumbers made of hundreds and tens (240, 870), sums of place values, and simple equations.
New words
place-value addend · xona qo‘shiluvchiequation · tenglamaunknown · noma’lumten · o‘nlik
Explanation
879 = 800 + 70 + 9 is a sum of place values. 240 = 2 hundreds 4 tens 0 ones. 407, 470 and 47 are all different numbers. In an equation the unknown number is written as a letter: 400 + x = 408. To solve it, x = 408 − 400 = 8.
Worked examples
613 = 600 + 10 + 3.
If 300 + a = 310, then a = 310 − 300 = 10.
Class activity
“Take it apart”: in pairs, one child says a three-digit number and the other writes it as a sum of place values in the notebook (782 = 700 + 80 + 2).
Practice
1
500 + 60 + 4 = ?
564
2
Solve: 700 + y = 706. y = ?
6
3
Solve: m + 40 = 640. m = ?
600
4
Write as a sum of place values: 413.
400 + 10 + 3