💯 Jack's Big Numbers

Two-digit maths all the way to one hundred — tens, ones, and nets full of footballs

What this is

Jack's Numbers stops at twenty. This is the sequel for the child who has outgrown it: sixty sums with two-digit numbers, in six steps that follow the order Year 1 is taught in.

	Step	Example
1️⃣	Tens and ones — read a number off the nets	🥅🥅🥅 ⚽⚽⚽⚽ → 34
2️⃣	Add ones, no bridging — the tens never move	23 + 4
3️⃣	A whole ten more, a whole ten gone	45 + 10, 47 − 10
4️⃣	Bridging — the ones spill into the next ten	27 + 5, 32 − 4
5️⃣	Whole tens	30 + 40, 100 − 40
6️⃣	What comes next — counting on in 2s, 5s and 10s	35, 40, 45, ?

The picture is always footballs, and always ten to a net. Seventy-five is seven nets and five loose balls, not a heap of seventy-five — the same tens rods they use at school. Taking away crosses the balls out where they stand, and taking away ten crosses out one whole net, so the number of nets is what changes.

🎮 How to play

1️⃣   Look at the nets 🥅

Count the nets in tens, then the loose ones. Every ball can be tapped and says its own number out loud — "twenty-one, twenty-two, twenty-three" — so counting on is always available when the sum is hard.

2️⃣   Pick the number 🔢

Four tiles, one right. The three wrong ones are the mistakes a six-year-old actually makes: one out, ten out, or the two digits the other way round (27 for 72). A wrong tap wobbles the tile, greys it out and costs nothing — there is no way to lose.

⚽   Goal!

The right tile pays a football, shows the whole sum with the answer in rainbow letters, and reads it back: "Twenty-seven! Twenty-three plus four is twenty-seven." Five right in a row gets On fire! 🔥.

🏁   Full time

After the sixtieth sum the full-time whistle goes, the football tally is shown, and Play again starts the whole thing over. The place in the list and the tally are kept on the device, so it can be picked up at the next sum tomorrow.

🎯 What it practises

• 🔟   Place value — seeing 75 as seven tens and five, which is the whole point of the nets
• ➕   Adding and subtracting to 100 — with and without crossing a ten
• 🔁   Counting on in twos, fives and tens from any starting number
• 👂   Hearing the number words — every number from zero to one hundred is spoken, including the awkward ones (forty, not "fourty"; ninety-nine)

🗣 The voice

Every line is a pre-rendered clip of Microsoft's neural en-GB-SoniaNeural voice — 254 of them: each question, each answer, each full sentence, and every number word to a hundred. The browser's own speech synthesis is only the fallback for a line with no clip, because on an iPhone it sounds like a robot and a six-year-old notices.

Everything the game can say is built in one block of index.html marked TEXT-CORE, and the phrase list the clips are rendered from is generated straight out of that block — so a new sum can never end up with no voice.

🎈 The other games

Game	What it is
📖 Jack's Words	Hear a word, build it from letter tiles, then read it in a sentence	▶ play
🥅 Jack's Match	Tell real words from decodable nonsense words, then spell by ear	▶ play
✏️ Jack's Letters	Finger-trace all 26 lowercase letters in the correct stroke order	▶ play
🔢 Jack's Numbers	Count, add and subtract with footballs — to 10, then to 20	▶ play
💯 Jack's Big Numbers	Tens and ones, adding and taking away all the way to 100	▶ play 👈 this one
🍎 Jack's Apples	Trace 1–20, then fill the missing numbers into the apple grid	▶ play
👀 Jack's Sight Words	The twenty most common English words on big cards — tap one and hear it read out	▶ play
♟️ Jackies Schach	Full FIDE rules with a coach that marks the safe squares (German)	▶ play

All eight on one start page: jackbenn.ing — homework games first, chess always last.

🛠 Built like this

Every game in this organisation is one self-contained index.html — no build step, no framework, no package manager, no analytics, and no network calls once the page has loaded. That is a deliberate constraint: a game a child depends on should still work in five years, and a parent should be able to read the whole thing in one sitting.

• Speech — pre-rendered clips played through Web Audio, with the Web Speech API as the fallback. The AudioContext is created inside the ▶ tap, because iOS refuses to start audio any other way.
• Progress — kept in localStorage on the device (jackBigIndex, jackBigFootballs). Nothing is collected, sent or stored anywhere else.
• Made for an iPad mini in either orientation and a phone: the footballs shrink until the whole sum fits the screen, so the tiles are never pushed out of reach and the page never scrolls. Finger-sized targets, no hover-only interactions, prefers-reduced-motion respected.

Run it locally:

python3 -m http.server 8000

The start page at jackbenn.ing is built from google814/Jack, which is the source of truth. The repos in this organisation are copies kept in step by tools/sync-game-repos.sh in that repo, so each game also has its own page and its own link.