# 300. Name that Number

Simple little starter for you today. Minimum preparation, personalised challenge.

Equipment

• Paper or whiteboards

Instructions

• Hand out mini whiteboards or use paper.
• Write the alphabet on the board.
• Assign each letter a value. You can go for the standard 1 to 26 or choose a mixture of big/small numbers – maybe a negative number or two.
• Get each student to write down their name and associated numbers.
• Write a target number eg 100 on your board.
• Each student must use the numbers of their name to make the target. If they can’t, they must get as close as they can.
• If they make that target either find another way or change the target number.
• Alternatively once they’ve finished they could use their classmate’s name – did they use the same method?

Variations

• You can make this as easy or difficult as you want by changing the target or the alphabet numbers.
• Throw in some fractions or decimals – go all the way and thrown in algebraic indices or standard form. You are the best person to judge your students’ level of challenge..
• You could allow surnames, you could insist all numbers are used.
• Put three alphabet variations on the board for mixed ability teaching.
• If you are teaching a class not in the English language (eg Welsh, Greek, Russian), where the alphabet is different, this still works just assign each letter/character a number in the same way.
• The possibilities are huge – have fun!

Note: this isn’t numerology, it’s proper Maths!

# 240. Cogged up

It’s amazing what maths you see when you go for a walk along a canal on a beautiful afternoon. After helping a canal boat through a lock, the following problem occurred to me: how many times must you turn the handle to raise the sluice gate?

Fact: The sluice is controlled by a series of cogs. The handle turns a ratcheted cog with eight teeth.

Fact: The handle turns a small cog with thirteen teeth.

Question: The next cog has ten teeth on a quarter of it’s circumference. How many is this in total?

Fact: This large cog is attached to a small cog with ten teeth, which lifts the vertical post.

Question: From the picture can you estimate how many teeth are on the vertical post?

Question: Given all this information how many turns does the handle need?
Extension: Look at this picture. What is the angle between the foot supports?

# 203. Sunny Surd Sunflower

Today we have a guest contributor to the Sandpit – my colleague BH.

His Year 9 class have been studying Surds. They have just completed two particularly difficult Tarsia puzzles on simplifying surds. He celebrated their success by getting the class to create a ‘Sunny Surd Sunflower’ – what a great way to celebrate springtime and achievement.

UPDATE: Inspired by the bright sunflower, my class created an AVERAGE caterpillar!

# 197. £40.95

Today we have a discussion starter question for you, inspired by a trip to the shops.

My shopping cost £40.95 today. What is the smallest number of coins required to make this amount?
If I paid with two £20s and a £10 note, what is the most efficient change?
Why would someone pay £41.05, as opposed to £41?

I purchased 17 items, do you have enough information to calculate the mean?
The most expensive item was £10, the cheapest was 45p. What does this allow you to calculate?
Two luxury items cost £9 in total. If I hadn’t bought these, what would the mean have been? Does this effect the range?

When I paid I was given this voucher:

What would the shopping have cost somewhere else?
What would the mean cost per item be after this discount?
What percentage discount is this?

You could also use this as a discussion starter about the number skills you use when you go shopping.

# 169. Chrismaths 4

On the fourth day of Christmas Maths Sandpit gave to me … another odd problem.

Image credit: misskyliem.wordpress.com