Counting, reading and writing numbers up to 20
Aprende
Counting means saying the numbers in order, one for each thing. If you have 7 counters, you touch one and say “one”. You touch another and say “two”. You keep going until the last one.
7 counters: we touch each one only once The last number you say is the total. To avoid counting a thing twice or missing another one, you can cover it or move it aside once you have counted it. If you start with a different one, the total comes out the same.
The numbers from 0 to 20 are written with digits. From 0 to 9 there is only one digit. From 10 to 20 there are two. 10 is a 1 and a 0. From 11 to 19, the 1 goes first and another digit comes after it: 13 is a 1 and a 3.
11 12 13 14 15 16 17 18 19 20 eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen twenty The numbers from 11 to 20, with their names From 13 to 19, the names end in “-teen”: seventeen is seven and ten. Eleven and twelve have names of their own. Look at the order of the digits: 12 and 21 are different numbers. 0 is a number too: it tells us there are none.
Worked examples
Ejemplo 1
Gus puts 9 packages in a row outside Mara’s shop. How many packages are there?
- Touch each package only once and say a number: 1, 2, 3, 4, 5, 6, 7, 8, 9.
- The last number you said is the total.
There are 9 packages.
¡Ojo! Many children count the first package twice and say 10.
Ejemplo 2
Julie wants to write the number “fourteen” with digits. What does she write?
- Fourteen is ten and four.
- You write a 1 first and then a 4.
She writes 14.
¡Ojo! Many children write 41, because they put the digits the wrong way round.
Ejemplo 3
Tony sees the number 18 on the handlebars of his bike. How do you say it?
- 18 is a 1 and an 8: ten and eight.
- You say “eighteen”.
You say eighteen.
¡Ojo! Many children say “eight” or “nineteen”: they do not read both digits.
Un reto para pensar
Count the spoons in your home one by one. Write how many there are, with digits and with words. Ask someone to count them too: do you both get the same number?
Practica
Rondas de 10 preguntas. Elige el nivel: