I dreamt I was with my dog approaching a house where we were going to live. I saw my bicycle was in the front garden, the wheels were planted in the soil. Approaching the front door I saw the house number clearly "57", turned to my dog and said "that's a good number, 5+7 = 12, 1+2=3"; that was it!
Not surprising I dreamt about my bicycle as I had a puncture yesterday and left my bike at the bicycle repair shop. Though the number 57 and actually calculating in my sleep, I thought that was something we could only do with our conscious minds!

You can calculate, symbolically calculate, but more about that further along the interpretation...

First we see you walking with your dog. A dog is a protective, loyal companion... a guardian somesort. So, as you walk towards the new home, we could see that as you being guarded home. A house symbolizes all the aspects of yourself, and for it to be the new home, this would suggest you are arriving at a new you. You then notice your bicycle. To ride one would indicate trying to find a balance in your life, but here you are simply seeing it. And that suggests the bike is a reminder to you that perhaps you need to "freewheel", relax and enjoy your time. This suggestions is emphasised by the fact that you noted and felt the need to describe how the wheels are planted in the soil... that is, the wheels aren't free, but fixed. On the other hand, a life that's firmly grounded can achieve a lot of emotional and spiritual freewheeling that ultimately will be beneficial for the material life too. The door is another suggestion regarding the fact you are about to enter a new stage in your life. You're not there yet, but you soon will be (otherwise you would be entering the door).

Now for the numbers... yes, you can calculate, just like you can talk and walk in a dream... it's just that meaning is not a rational one, but a symbolical one. So, it's not surprising that the calculations you do are symbolical ones (numerology)... your brain was numerologically (symbolism of numbers) calculating the meaning of the number 57, which is 12 and which is 3. And I suggest to look up the numerological meaning of both numbers. In numerology you usually add the numbers until you have one number below 10... there are a few exceptions to that, and one of the numbers is 12. 12 stands for completion, harmony. Jezus needed 12 apostles to complete his circle of closest followers. When his journey on earth was complete he broke 12 breads at the last supper. So, the dream indicates that you have completed a cycle in life, which coincides with entering a new phase, a new you, a new home in your life. 12 is also the symbol of manifesting the trinity in the four corners of the horizon. And so we come to the number three, the number of the holy trinity : soul, earthly life and wisdom combined. LIke a bicycle the number 3 represents stability... try to knock over a pyramid But it also means creation, and thus creativity. Creativity is a way to express yourself. So, I would say that the new phase in your life is one where you have the time and the freedom to spend on expressing yourself in a creative way.

Lovely dream