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Ffocws dysgu

Dysga gyfrifo symiau canrannol yn seiliedig ar 10%.

Mae'r wers hon yn cynnwys:

• cyflwyniad i waith canrannau
• gwahanol ddulliau i ddod o hyd i ganrannau
• dau weithgaredd

Learning focus

Learn to calculate percentage quantities based on 10%.

This lesson includes:

• an introduction to work on percentages
• different methods to find percentages
• two activities

Canrannau

Ystyr ‘canran’ yw ‘y cant’.

Os yw 70 y cant o’r boblogaeth yn berchen ar anifail anwes, mae hynny’n golygu bod 70 o bob cant o bobl yn berchen ar anifail anwes.

Ystyr y symbol % yw ‘y cant’.

Percentages

Percent means 'per 100'.

If 70 percent of the population own a pet, this means that 70 out of every hundred people own a pet.

The symbol % means 'percent'.

Yn y diagram hwn, mae 30 allan o 100 sgwâr wedi eu lliwio. Felly mae 30% wedi eu lliwio.

In this diagram, 30 out of 100 squares have been shaded. So 30% has been shaded.

Dod o hyd i ganran rhif ar gyfrifiannell

Er mwyn dod o hyd i ganran rhif ar gyfrifiannell, rhaid newid y canran i mewn i ddegolyn a'i luosi gyda'r rhif, er enghraifft:

25% o 60 yw 0.25 x 60 = 15

How to find a percentage on a calculator

To find a percentage of an amount on a calculator, turn the percentage into a decimal and multiply it by the amount.

So 25% of 60 is 0.25 x 60 = 15

Sut i gyfrifo canran

Y dull 1%

Un ffordd i ffeindio canran swm yw cofio mai 1 y cant o swm yw un canfed ohono. Felly, er mwyn dod o hyd i 1 y cant o swm penodol, gelli di ei rannu gyda 100.

Enghraifft

I ddod o hyd i 1% o £400, rhanna'r £400 gyda 100 a'r ateb yw £4.

Pan rwyt ti'n gwybod 1% o £400, gelli di wedyn ddod o hyd i ganrannau eraill wrth luosi, er enghraifft:

2% o £400 yw 2 x £4 = £8.

30% o £400 yw 30 x £4 = £120 ac yn y blaen.

Y dull degol

Ffordd arall i ddod o hyd i ganran swm yw defnyddio'r ffaith bod rhannu â 100 yr un peth â lluosi â 0.01.

Gelli di ddefnyddio'r dull hwn i ddod o hyd i unrhyw ganran.

Enghraifft

1% o £400. Lluosa £400 gyda 0.01 a chei di £4.

2% o £400. Lluosa £400 gyda 0.02 = £8.

30% o £400. Lluosa £400 gyda 0.30 = £120.

Yr enw ar hyn yw'r dull degol. Os gallet ti newid canran i mewn i ddegolyn yn dy ben - er enghraifft, wrth ei ddychmygu fel ceiniogau mewn punt - mae'r dull hwn yn gyflym ar gyfrifiannell.

How to calculate percentage

The 1% method

One way to find the percentage of an amount is to remember that 1 per cent of an amount is one hundredth of it. So to find 1 per cent of an amount, you can divide it by 100.

For example to find 1% of £400, divide it by 100 and you get £4. Once you know 1% of £400, you can then find other percentages by multiplying.

For example:

2% of £400 is 2 x £4 = £8.

30% of £400 is 30 x £4 = £120, and so on.

The decimal method

Another way to find a percentage of an amount is to use the fact that dividing by 100 is the same as multiplying by 0.01.

You can use this method to find any percentage.

Example

1% of £400. Multiply £400 by 0.01 and you get £4.

2% of £400. Multiply £400 by 0.02 = £8.

30% of £400. Multiply £400 by 0.30 = £120.

This is called the decimal method. If you can turn a percentage into a decimal in your head – for instance by imagining it as pennies in the pound – this method is quick on a calculator.

Gweithgaredd 1 / Activity 1

Ateba'r cwestiynau isod gan ddefnyddio'r dull 1%.

1. Mae gan Robin focs sy’n dal 200 beiro. Mae 10% o’r beiros yn goch. Faint o feiros coch sydd yna? (Beth yw 10% o 200?)

2. Mae 300 o lyfrau mewn stafell ddosbarth. Mae 20% ohonyn nhw'n goch. Sawl llyfr sy'n goch? (Beth yw 20% o 300?)

3. Mae ffrog mewn siop yn costio £500. Mae Siân yn cael gostyngiad o 30%. Faint yw gostyngiad Siân? (Beth yw 30% o £500?)

Answer the questions below using the 1% method.

1. Robin has a box which holds 200 biros. 10% of them are red. How many red biros are there? (What is 10% of 200?)

2. There are 300 books in a classroom. 20% of them are red. How many books are red? (What is 20% of 300?)

3. A dress in a shop costs £500. Siân has a 30% discount. How much is Siân's discount? (What is 30% of £500?)

Gweithgaredd 2 / Activity 2

Ateba'r cwestiynau isod gan ddefnyddio'r dull degol.

Answer the questions below using the decimal method.

1. Beth yw 3% o £200? - What is 3% of £200?

2. Tyrd o hyd i 7% o £400. - Find 7% of £400.

3. Canfydda 15% o £300. - Find 15% of £300.

Nodiadau i rieni

Ar ddiwedd y wers hon, bydd disgyblion yn:

• gwybod sut i ddod o hyd i ganran gan ddefnyddio'r dull 1%
• gwybod sut i ddod o hyd i ganran gan ddefnyddio'r dull degol
• deall sut i ddod o hyd i ganran gan ddefnyddio cyfrifiannell

Notes for parents

After the lesson, pupils will:

• know how to find percentages using the 1% method
• know how to find percentages using the decimal method
• understand how to find percentages using a calculator