# Suma primeiro

Addition. Tree algorithm

CAUTION: Begin grouping on the left, that is, by higher values

WORKSHEET (numbers with 3 digits)

Sum of the numbers of a set

Check with rods if the addition is correct

The Paco's sack

This exercise consists of grouping the numbers into sets of 10 units and then adding them.

What rod you need in order to complete the number 10?

In this exercise you must indicate which rod is necesary to complete 10. Remember the friends numbers.

Numbers friends

Two numbers are friends if between numbers sum 10

## 5 and 5

(The number five is a friend itself)

## 6 and 4

(We can draw a number four if you rotate 90° the number six)

## 7 and 3

(the number 7 is drawed with 3 lines)

## 8 and 2

(the number 8 has two holes)

## 9 and1

(the number nine has one hole)