"6 + 9" is easy for me, but for some reason, I need some time to calculate "7 + 9"...

Don't you have such combinations of numbers that feel a little more difficult for you?
For me, the author of this app, the combinations containing 8 or 9 were difficult.
I felt it also hard to calculate the total price of products every time I went shopping.

So, I decided to develop this app, considering my own training too, and I actually improved my addition skills to some degree already by testing this app again and again while I was developing it.
I'm sure you'll also improve your own skills as I did!

I hope you enjoy the app as well as improving your mental addition ability.

HOW TO USE

Numbers are displayed one by one at specified time intervals.
Add up those numbers in your mind.

STAGES

There are 20 stages with a combination of 5 kinds of digits (1 to 5 digits) and 4 intervals (6, 3, 1 and 0.5 seconds).
The highest stage is 5 number of digits with 0.5-sec intervals.
You will be a real "expert" if you ever reach such a high level!

Each stage has its own name.

- 1 digit, 6-sec intervals: "Shell" stage
- 1 digit, 3-sec intervals: "Prawn" stage
- 1 digit, 1-sec intervals: "Turtle" stage

and so on...

EXPERT MEDALS AND LEVELS

You'll get an expert medal if you answer correctly 5 times in a row at a stage.
The highest among all the stages where you've obtained medals indicates your current level.
How far will you be able to go? Try it now!

PRACTICE FUNCTION

You can switch the values by tapping on the forward/back buttons at your own pace.
Try as many times as you like until you get used to it, and you'll be good enough to feel the stage is much easier than before.

REVIEW FUNCTION

After each challenge, you can review the values you just saw in the challenge.
Make use of it to gain enough confidence to get the right answer within the time limitation.

OTHER USEFUL FEATURES

- Multiple challengers can be registered, so the whole family can enjoy the app on a single device.
- You can set one of preset theme colors, which makes it easier to distinguish a challenger from others on a device.
- Your successful challenge result can be shared on SNS with an image attached.