# Tenths

### Purpose:

You can help your child develop their knowledge of the number of tenths in whole numbers. Knowledge of tenths builds on knowledge of tens and hundreds in whole numbers which is developed in the activity Tens and Hundreds. You may like to complete Tens and Hundreds before trying this activity.

### What you need:

Sales brochures, for example supermarkets and large discount stores. Choose catalogues which have easily read prices.

### What to do:

Select an item, for example a packet of cereal that costs \$3.80. Ask your child about the number of ten cent pieces they could use to buy the item.
How many ten cent pieces would you need to buy this box of cereal? Why?
You would need 38 ten cent pieces because that would be 380 cents, which is \$3.80.

If your child is having difficulty, remind them that there are 10 ten cent pieces in every dollar. Use this knowledge to build up to the price of the item. For example, for an item costing \$6.50:
How many ten cent coins are there in \$1? (10)
How many would there be in \$2? (20)
How many would there be in \$3? (30)
How many would there be in \$4? (40)
How many would there be in \$5? (50)
How many would there be in \$6? (60)
How many ten cent coins would there be in \$6.50? (65)

Repeat using different items and different prices.

Talk about ten cents as being one tenth of a dollar.
There are 10 ten cent coins in one dollar, so one ten cent coin is one tenth of a dollar.
There are one hundred cents in a dollar. Ten is one tenth of one hundred because      there are ten tens in one hundred.

When children are confident with these questions, ask them about the number of tenths in whole numbers.
How many tenths are there in all of 3? 30 tenths
How many tenths are there in all of 81? 810 tenths

### What to expect your child to do:

• Children should know the number of tenths in a whole number. For example there are 20 tenths in 2, 400 tenths in 40 and 5000 tenths in 500.
• Knowledge of tenths follows from knowledge of tens and hundreds in whole numbers. Before children learn about tenths they need to know, for example:
In 563 there are 563 ones in total, 56 tens in total and 5 hundreds in total.
In 7 814 there are 7 814 ones in total, 781 tens in total, 78 hundreds in total, and 7 thousands in total.

### He Kupu Māori:

 tenths hautekau

### He Whakawhitinga Kōrero:

• Kia hia ngā tekau hēneti hei hoko i tēnei pouaka pata kai? (How many ten cents to buy this box of cereal?)
• Whakamāramatia mai. (Explain it to me.)
• Kia toru tekau mā ono ngā tekau hēneti, nā te mea ka eke tērā ki te toru rau ono tekau hēneti. Ko te toru tāra ono tekau hēneti tērā. (You would need 36 ten cent pieces because that would be 360 cents, which is \$3.60.)
• E hia ngā tekau hēneti kei roto i te kotahi tāra? (How many 10 cents are there in \$1?) (10)
• E hia ngā tekau hēneti kei roto i te rua tāra? (How many 10 cents are there in \$2? (20)
• E hia ngā tekau hēneti kei roto i te toru tāra? (How many 10 cents are there in \$3? (30)
• E hia ngā tekau hēneti kei roto i te whā tāra? (How many 10 cents are there in \$4? (40)
• E hia ngā tekau hēneti kei roto i te rima tāra? (How many 10 cents are there in \$5? (50)
• E hia ngā tekau hēneti kei roto i te ono tāra? (How many 10 cents are there in \$6? (60)
• E hia ngā tekau hēneti kei roto i te ono tāra rima tekau hēneti? (How many 10 cents are there in \$6.50? (65)
• Tekau ngā tekau hēneti kei roto i te kotahi tāra. Ko te hautekau tāra tērā. (There are ten lots of ten cents in a dollar. That is one tenth of a dollar.)
• E hia ngā hautekau tāra kei roto i te rua tāra? (How many tenths of a dollar are there in \$2?) (20)
• E hia ngā hautekau kei roto i te toru? (How many tenths are there in 3?) (30)
• E hia ngā hautekau kei roto i te toru ira rima (3.5)? (How many tenths are there in 3.5?) (35)